netdev - Re: [PATCH] ipv4: arp_notify address list bug

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Message-ID: <4ACAB5BC.1020307@gmail.com>
Date:	Tue, 06 Oct 2009 05:13:00 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Stephen Hemminger <shemminger@...tta.com>
CC:	David Miller <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [PATCH] ipv4: arp_notify address list bug

Stephen Hemminger a écrit :
> This fixes a bug with arp_notify and also adds a small enhancement.
> 
> If arp_notify is enabled, kernel will crash if address is changed
> and no IP address is assigned.
>   http://bugzilla.kernel.org/show_bug.cgi?id=14330
> 
> The fix is to walk the (possibly empty) list when sending
> the gratuitous ARP's.

> 
> -				 NULL, dev->dev_addr, NULL);
> +		/* Send gratitious ARP to notify of link change */

	/* gratuitous */

> +		if (IN_DEV_ARP_NOTIFY(in_dev)) {
> +			struct in_ifaddr *ifa;
> +			for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next)
> +				arp_send(ARPOP_REQUEST, ETH_P_ARP,
> +					 ifa->ifa_address, dev,
> +					 ifa->ifa_address, NULL,
> +					 dev->dev_addr, NULL);
> +		}

This sends a broadcast storm if device has a long address list.

Maybe we should change arp_notify to an INTEGER to be able to give a limit.

If people used to set arp_notify to 1, they wont be surprised too much.

I suggest splitting patch in two parts, one to fix the bug for linux-2.6 and stable,
and another one for net-next-2.6 for the enhancement ?

Thanks

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